It’s good for you. Without intermittent periods of reflection and rest, you will never keep up with the pace of your life. Some people turn to meditation and others to daydreaming; both serve the same purpose: recharge and reorient. Perhaps more important than rest, short quiet periods in your day help you process everything. When you break from mental stimulation and general busyness, you give your brain a moment to pass your experiences and newly formed lessons to memory. Catching your breath helps you sort through the data of your life and think more clearly thereafter.
Stop, take a breath, and zone out. Right now. When you can. And never feel guilty about it.